The effects of the repair operations and replacement of the elastomeric bearings on the modal characteristics of a highway bridge

In this paper, the extraction of the dynamic properties of a two span simply supported pre-stressed concrete skew highway bridge has been reported. The experimental work has been carried out according to a predetermined repair program involving the replacement of the elastomeric bearings. The operational modal analysis (OMA) technique has been used for the extraction of the modal properties of the bridge. The dynamic parameters of the bridge have been derived with the use of the frequency domain decomposition (FDD) as well as the stochastic subspace identification (SSI). Five modal tests have been carried out during different stages of the repair operations. One of these tests has been performed under normal traffic and the rest of the experiments have been carried out in the condition of traffic closure. Supporting numerical analyses have demonstrated close agreement between experimental and numerical results. In addition, the effects of the variation of the values of the shear modulus of the elastomeric bridge bearings on the dynamic properties of the bridge have been investigated. As a result of the experimental and numerical studies, it has been demonstrated that some additional retrofit measures also needed to be taken.